Containers of the type disclosed in NL1017159 are employed across the globe for the transport of freight goods, by land, sea and air. Global trade and distribution imbalances frequently necessitate the transport of empty containers from large consumption markets to regions of mass production and manufacture. In order to alleviate the cost of transporting empty containers, collapsible containers have been developed. These containers can be folded when empty into a collapsed or stowed condition in which they occupy significantly less volume than in their assembled or erected condition, thus allowing for more efficient transportation of the containers when empty.
Assembly and disassembly of collapsible containers must take place in a safe and reliable manner. Frequently, the size and weight of the container walls are such that heavy lifting equipment such as forklifts must be employed, complicating operation and increasing the burden of assembly/disassembly. It is therefore desirable to simplify as far as possible the procedure for assembly and disassembly of collapsible containers. One known type of collapsible container 102 is illustrated in FIGS. 1a to 1c and comprises a base 104, side walls 106, 108 and a roof 110. The walls 106, 108 are hinged to the base 104 at hinges 112, 114 such that they may rotate about the hinges and fold onto the base 104. The roof 110 is connected to the opposed side walls 106, 108 via rigid connection members 116, 118, each of which is connected via a first hinge 124, 126 to a respective side wall 106, 108 and via a second hinge 120, 122 to the roof 110. The connection members may thus pivot about each end, allowing for raising of the roof 110, pivoting motion of the walls 106, 108 beneath the roof 110 and then lowering of the roof 110 onto the collapsed walls 106, 108, as illustrated particularly in FIG. 1b. The connection members allow a connection to be maintained between the side walls 106, 108 and the roof 110, during the process of collapsing the walls.
FIG. 1c illustrates the structure of the collapsible container in more detail. It will be appreciated that, during collapsing of the walls 106, 108, the connection members 116, 118 must pass through an angle approaching 270° with respect to the walls 106, 108. In order to allow for this range of motion, it is necessary to leave large recesses 117 in the top of each wall (106,108) or roof (110), and these recesses 117 impact on the ability to seal the joint between the walls and the roof. In practice, it is extremely difficult to establish a seal between the roof 110 and walls 106, 108, while leaving the necessary clearance, and consequently, the container 102 cannot be made watertight. This is a considerable disadvantage as if sea water enters the container 102 in high seas, the contents of the container can be seriously damaged.
Another known container type that seeks to address the issue of sealing between the roof and walls of the container is illustrated in FIGS. 2a and 2b. This container 202 also comprises a base 204, opposed side walls 206, 208 and a roof 210. The walls 206, 208 are hinged to the base 204 at hinges 212, 214 such that they may rotate about the hinges and fold onto the base 204. The roof 210 is connected to the opposed side walls 206, 208 via rigid connection members 216, 218. Each connection member comprises a first end which is connected via a first hinge 224, 226 to a respective side wall 206, 208. The second ends of the connection members 216, 218 are formed as runners 230, 232, adapted to be slidably received within a respective slot or channel 234, 236 formed on the roof 210. According to this construction, it is possible to lift the roof 210, pivot the side walls 206, 208 towards the base 204 and subsequently lower the roof 210 without the need for excessive pivoting of the connection members 216, 218. The connection members merely slide within the slots 264, 236 formed within the roof 210. Owing to this sliding motion, the container can be constructed without the need for large clearance between the walls 206, 208 and the roof 210, and a watertight seal may be obtained between the walls 206, 208 and the roof 210. A further example of a collapsible container of this type is disclosed in FR2699513
Although the container of FIG. 2 addresses some of the clearance and sealing issues experienced with the container of FIG. 1, other issues of assembly and disassembly are known to arise with this type of container. In order to accommodate the motion required for assembly, the slot and slider system must be relatively long and complex. In addition, it is necessary to maintain the roof in accurate alignment with the base during assembly and disassembly of the container. Misalignment of the roof with respect to the rest of the container can cause the slider mechanisms to jam during motion, placing excessive forces on the slider joints. In practice, it is extremely difficult to maintain accurate alignment of the roof when lifting, for example with a reach stacker or a crane. The connection members, sliders and hinges must therefore be highly robust to withstand the large loads experienced during assembly and disassembly of the container. Even with extremely robust connections, a trained operator is required and there remains a risk that the connections between the connection members and the roof or the walls may fail.
Japanese patent publication JP H05 16694 U describes a foldable pallet container. This publication discloses a different method of folding compared to the above publications and to the present invention. Side walls need to be totally removed before folding and the roof is directly fixed to the side walls at its upper end and via a linkage.
This invention seeks to address some or all of the above mentioned disadvantages associated with known collapsible transport containers according to NL1017159 and FR2699513.